United Nations Secretary General Ban ki-moon speaks with the media following his briefing at the United Nations headquarters in New York on March 14, 2014. Photo Credit: EPA / Andrew Gombert

UNITED NATIONS - UN Secretary-General Ban Ki-moon left New York for Russia and Ukraine Wednesday afternoon in a mission designed to defuse the crisis in Crimea.

Ban is scheduled to meet Thursday with Russian President Vladimir Putin and Foreign Minister Sergey Lavrov, UN officials said. He then heads Friday to Kiev, Ukraine's capital, where he is to meet with acting President Oleksandr Turchynov and Prime Minister Arseniy Yatsenyuk.

Haq added that Ban was invited by Moscow and Kiev, but it was unclear whether he could succeed where his own envoys in recent weeks have not.

"What he has made clear is that he wants to build constructive dialogues," Haq said. "He's made clear that we are at a crossroads and, as he has said, the focus must be to engage in direct dialogue between Moscow and Kiev aimed at agreeing on specific measures that will pave the way toward a diplomatic solution."

While in Ukraine, Ban is set to meet with the UN Human Rights Monitoring Mission.

Both UN officials have visited Ukraine and have provided bleak reports on the crisis they contend has been worsening, saying there are reports of extrajudicial killings, torture and other human rights violations.Simonovic said he was blocked from entering Crimea last week, while another envoy, Secretary-General's Special Adviser Robert Serry, was threatened in Crimea by unidentified men -- some armed and uniformed and some unarmed -- who he said demanded that he leave the area.

"Now, the referendum has taken place, but the national and international legal status of Crimea has not changed," said U.S. Ambassador to the UN Samantha Power after hearing Simonovic and Eliasson at the Security Council yesterdayon Wednesday. "A thief can steal property, but that does not confer the right of ownership on the thief."

Vitaly Churkin, Russia's ambassador to the UN said the referendum had corrected a mistake in history, the transfer of Crimea from Russia to Ukraine in 1954 by then-Soviet Premier Nikita Khruschev.

"A historic injustice has been righted," Churkin said.

The developments come after several months of turmoil in Ukraine, including the ouster of President Victor Yanukovich, who fled the country in February amid protests after he declined to associate with the European Union.

The population's loyalties in Ukraine have long been split between Russia and western Europe.

Russia on Saturday vetoed a resolution in the Security Council that declared illegal Crimea's referendum to secede from Ukraine. Russia's veto was the only "no" vote. China, a longtime ally of Russia, abstained from voting.